Shami Chakrabarti, David Davis, Lord Macdonald and others say Ken Clarke's plans undermine essential scrutiny of government
Extending secret hearings into civil courts will undermine effective scrutiny of government operations in the "war on terror", according to prominent civil liberties activists and lawyers.
In a letter to the Guardian, the director of Liberty, Shami Chakrabarti, the Conservative MP David Davis, Lady Kennedy QC, the former director of public prosecutions Lord Macdonald QC and others warn that the government's justice and security green paper violates "basic principles of the common law".
Their criticism comes as the justice secretary, Ken Clarke, gives evidence to parliament's joint human rights committee on the impact of the proposals that will prevent claimants being told of the evidence against them.
"The worst excesses of the war on terror were revealed by open courts and a free media. Yet the justice and security green paper seeks to place government above the law and would undermine such crucial scrutiny," the letter – also signed by the Rev Nicholas Mercer, human rights lawyer of the year, and Dinah Rose QC, who has worked a special advocate in security sensitive cases – declares.
"It would permit the extension of closed material procedures, in which claimants and their lawyers are excluded from court and refused sight of government evidence, to any civil claim, whenever a minister considers that openness is against the 'public interest'.
"This violates two of the most basic principles of our common law system: the right of every party to know the case against them, so that they can answer it; and the principle that there must be equality of arms between parties in court. It would permit secret hearings, and the giving of secret judgments by courts, accessible only to the government."
The proposals have been introduced in response to claims brought by those who have been mistreated or detained at Guantánamo Bay. "Surely," the letter concludes, "the response to the exposure of British complicity in kidnap and torture ought to be to ensure that such events will never be repeated; not to create a system that is designed to ensure that they could never be exposed?"
The justice secretary has attempted to allay fears by insisting that closed material procedures (CMPs) will only apply to a "tiny" number of civil cases in "very limited circumstances".
Writing in the Daily Mail before his appearance before the select committee on Tuesday afternoon, Clarke explained: "I have heard, loud and clear, the fears from many campaigners including special advocates, that the government's proposals are too broadly drawn and might even mean that the likes of the Stephen Lawrence trial and De Menezes case could end up in secret.
"That's not what anyone wants. The reforms we are proposing will apply only in very limited circumstances, in a tiny number of civil cases, where the public safety could otherwise be put at risk.
"Under these plans, there will be no change to anyone's right to make their allegations public. Courts would continue to hear the vast majority of cases in the open. Closed hearings would be limited to evidence that would genuinely endanger the most sensitive informant that we rely on to protect the public."
Sir Malcolm Rifkind, chairman of the parliamentary intelligence and security committee, has argued that co-operation with foreign intelligence agencies such as the CIA would be endangered if secrets were exposed in court.
"It is essential that our courts are able to handle intelligence material, and that that material is properly protected," he has warned. "It is a fundamental principle of intelligence-sharing that such exchanges are kept confidential."
As well as the government, many Labour politicians have supported the main thrust of the reforms. The former home secretary David Blunkett has described the plans as "appropriate".
The Liberal Democrats appear more divided. Sir Menzies Campbell supported the proposals in parliament on the grounds that they would help protect the UK's special intelligence relationship with the United States, Canada, Australia and New Zealand. Other MPs have expressed misgivings.
In one of the latest consultation submissions published by the Cabinet Office, Cambridgeshire police point out that the green paper "will have far-reaching consequences for the use of covert tactics within law enforcement agencies".
The supreme court is due to deliver judgment on the workings of CMPs in special immigration tribunals on Wednesday, a decision that may well influence the debate.